The present invention relates to an improved mill roll for use in a mill for grinding material, such as sugar cane, and for extracting juice, for example sucrose, therefrom.
As is known in the sugar cane industry, the purpose of a cane mill is to grind sugar cane while extracting sucrose therefrom. A conventional cane mill includes a bottom roll and a top roll, the two rolls rotating in directions such that a blanket of sugar cane being nipped therethrough is ground. Sucrose extraction is achieved in conventional cane mills by providing "messchaert" grooves in the bottom rolls, such that as the cane blanket is nipped and ground between the two rolls, the sucrose juice is drained downwardly through the messchaert grooves. An inherent disadvantage of such conventional cane mills is the fact that a substantial amount of the extracted juice invariably becomes trapped in the upper part of the cane blanket and becomes reabsorbed during passage of the blanket between the two rolls.
One attempt to alleviate this conventional disadvantage is disclosed in U.S. Pat. No. 3,969,802, wherein the upper roll has formed in the periphery thereof a plurality of circumferentially extending grooves. A plurality of channels are formed within the body of the upper roll and extend axially thereof. A plurality of round holes extend substantially radially from the bottom of the grooves and communicate with the channels. Thus, during operation, juice at the upper part of the blanket is extracted by passing radially inwardly through the round holes and then axially through the channels. However, while this arrangement has been an improvement over previous cane mills, certain disadvantages exist. Thus, the round holes tend to become clogged. Furthermore, the manner of formation of the round holes, and subsequent repair or replacement thereof, is difficult.